modbus communication

Dear Experts,

We are using siemens original program which has been downloaded fron siemens web site. In program we are trying to communicate with one modbus slave. If we use read function (function code 03H 0r 04H) or write function (function code 06H) then it is communicating perfectly with slave. But if we use multiple write function (function code 10H) then it is not communicating & error counter ("SEND_WORK_DB_SI_0".S_SEND_SI_WORK_CNT_ERR) is keep on incrementing if we initialize the communication from M120.7.

S7program is attached for your refrence.

So what may be the problem?help?